At thirty one minutes after eleven, Bert knocked on a door on the fourth
floor of a luxury apartment downtown. The door bore a large number, 412.
Below it was a small metal plate containing a slip of paper on which was
written, "The Android Sisters."

After a long pause, Dave said, "Try it again."

Bert knocked again.

There was another, even longer pause.

Dave pressed his ear up against the door. "I don't hear anything."

"Maybe they're at work," ventured Paul.

"Or if not, maybe someone there can tell us where they are,"
added Peter.